OS X Mountain Lion: About Thunderbolt
With your Mac computer’s Thunderbolt port, you can connect your Mac to a display or an external device for high-speed data transfer.
If your display uses a Mini DisplayPort, you can connect it to the Thunderbolt port on your Mac. And with the appropriate adapter, you can connect your Mac to a display that uses DisplayPort, DVI, HDMI, or VGA.
Use only Thunderbolt cables with Thunderbolt devices, and only Mini DisplayPort extension cables with Mini DisplayPort devices. If you use the wrong cable, the device won’t work even though the cable’s connectors fit your device and your Mac.
The Thunderbolt port on a Mac provides power, so many Thunderbolt devices directly connected to your Mac don’t need their own power cords. Check the documentation that came with your device to see if the device needs more power than the Thunderbolt port provides and must be plugged in.
If you have a portable Mac, using a Thunderbolt device without its own power cord can cause your portable’s battery to become depleted faster. If you plan to use such a device for an extended period, it’s a good idea to connect your portable Mac or your Thunderbolt device to a power source. When connecting a Thunderbolt device to a power source, be sure to disconnect the device from your Mac first, then connect the device to a power source, and then reconnect the device to your Mac. Otherwise, the device still draws power from your Mac.
You can connect multiple Thunderbolt devices to each other, and then connect the chain of devices to the Thunderbolt port on your Mac.
Only the device directly connected to your Mac can get power from the Thunderbolt port. The rest of the devices in the chain must be powered by separate power adapters.
A DisplayPort device can be part of the chain, but it must be at the end. For example, if you want to connect both a Thunderbolt hard disk and a DisplayPort display to your Mac, connect the display to the hard disk and then connect the hard disk to your Mac.
If you use Boot Camp to run Windows on your Mac, read this support article to learn how to use Thunderbolt devices with Boot Camp: